31 Oct 2011

Using IUCN-Data, ArcMap 9.3 and R to Map Species Diversity

..I'm overwhelmed by the ever-growing loads of data that's made available via the web. I.e., IUCN collects and hosts spatial species data which is free for download. I'm itching to play with all this data... And, in the end there may arise some valuable outcome:

In the below examples I made a map for amphibian species richness - without much effort. I used a 5x5 km grid (constant areas, provided by Statistik Austria) and amphibian species ranges and intersected this data to yield species numbers per grid-cell. For aggregation of the tables from the polygons produced by the intersection I needed to switch from ArcMap to R because ESRI's "Summary Statistics" only cover MIN, MAX, MEAN, FIRST/LAST... and there is no easy way to apply custom functions. So, I just accessed the dbf that I wanted to aggregate with R and did the calculations there.. then reloaded the layer in ArcMap and was done..

24 Oct 2011

A Simple Example for the Use of Shapefiles in R

A simple example for drawing an occurrence-map (polygons with species' points) with the R-packages maptools and sp using shapefiles.
HERE is the example data.

23 Oct 2011

A Little Webscraping-Exercise...

In R it's quite easy to pull out anything from a webpage and I'll show a little exercise in doing so. Here I retrieve all blog addresses from R-bloggers by the function readLines() and some subsequent data processing.

12 Oct 2011

Yet Another One.. Animation with saveHTML / saveVideo from Package ANIMATION

...some more playing with saveHTML, as.raster() and rasterImage(), producing a "flickering screen":

How to Link to Files at Google Docs for Direct Download

...Google doesn't tell you this, as far as I know - so, if you want to link to a file at Google Docs for direct download you can use the following address scheme:


You can copy your individual file id from within the "Share..."-dialogue. Here you also need to put the share settings to "public" or to "anyone with the link"

a HTML example for this link to a pdf-file:

10 Oct 2011

Plot Animation with Imported Images

...I really dig the animation package! ..so here's the outcome of my firsts encounters with saveHTML() - I produced an animation with pre-existing images by utilizing the functions readJPEG() and rasterImage() from the R-packages jpeg and ReadImages. Credit goes out to xingmowang (nzprimarysectortrade-blog) from whom I picked up the concept of putting images to the plot region of a graph produced with the animation-functions.